Patent GB-1350051-A (GB)
Title: Enclosure for loudspeakers
IPC: H04R1/28
Filed: 1972-02-15
Abstract: 1350051 Loud-speaker enclosures J M TEIRE 14 June 1972 [15 Feb 1972] 6952/72 Headings H4J and H4X A loud-speaker enclosure comprises a hollow shell of ceramic material having at least one sound transmissive aperture adjacent which is a support, within the shell, for a loud-speaker. The loud-speaker diaphragm separates the at least one aperture from a major portion of the space within the shell. The ceramic material is preferably clay-based to provide high mass, and it may be glazed. Upper and lower parts of the shell may have the same or different decorative effects. For multi-channel sound reproduction all enclosures of a set may be similar or glazed differently. A ceramic enclosure 2 (Fig. 1) has the form of a truncated ovoid member 4 supported on a drum-like base 3. A horizontal shelf 5, centrally apertured, has holes 7 by which a loud-speaker 1 is secured. The loud-speaker 1 may be mounted on a wooden frame secured to the shelf 5, a resilient gasket being interposed. An aperture in the base of member 4 is large enough for insertion of the loud-speaker 1. Sound transmissive apertures 8 are provided above the shelf 5. A loud-speaker lead 9 passes through a hole 10 in base 3. Sound absorbent material 21 fills the enclosure 2. The base 3 has a flange 11 which fits within a recess in the lower part of member 4. Bolts (16), Fig. 2, not shown, secured by nuts (17) pass through aligned holes (14, 15) in the base 3 and member 4 to provide rigid connection. The nuts and bolts may be of nvlon. If they are of metal, soft resilient washers (18, 19) are placed between them and the ceramic material. A felt or other resilient gasket (20) is interposed between base 3 and member 4. Alternatively, base 3 and member 4 are secured by adhesive. In an alternative embodiment (Fig. 3, not shown) the base 3 and ovoid member 4 are integral up to and including a loud-speaker shelf (32) centrally apertured to accept a loud-speaker 1 mounted on a supporting board (34). The interior of the ovoid member has rounded-off edges. A horizontal spider (38) of radially extending arms strengthens the enclosure. Above the loud-speaker (1) is a cap (35) secured by rupturable adhesive to the shelf (32)- Preferably an annular projection in the underside of the cap (35) fits into a circular recess (36) in the upper part of the shelf (32). The cap (35) is apertured to provide sound radiation. Yet another embodiment uses two loudspeakers 41, 42 (Fig. 4). A lower portion 43 of the enclosure extends upwardly to a shelf for supporting loud-speaker 41. Loud-speaker 42 is supported on a radially inwardly extending flange 43a. A drum-like base 44 extends between flange 43a and a bottom wall 43b and has sloping apertures 45 which, together with a sound reflector cone 50 (e.g. of exponential form) assist in deflecting sound radially rather than axially. A cap 47 which is secured similarly to that of Fig. 3, has shaped apertures 48 to deflect sound from loud-speaker 41 radially outwardly. In an alternative arrangement (not shown) loud-speaker 41 is mounted on cap 47. Loud-speaker 41 may reproduce high frequencies while loud-speaker 42 reproduces lower frequencies or the frequency ranges of the two loud-speakers may be alike. A reflector cone, similar to cone 50, may be provided for loudspeaker 41. A small aperture 51 provides equalization of slow changes of atmospheric pressure.